VMS panels cause congestion?

VMS panels are widely used to provide information to road users. For instance, they indicate congestion downstream the location of the VMS panel. VMS panels are also used to warn drivers for incidents and provide other, general, information to drivers. Since recently, a new type of VMS panels is being implemented, which is not placed above the carriage way but immediately next to the carriageway. The new type of VMS panels is also used for all sorts of messages.

Both types of VMS panels require drivers to divert their attention slightly away from their driving field of view in order to read the information displayed. The question is if the VMS panels, depending on the information displayed, distract drivers to the extent that congestion may be caused by the panel and if this effect is influenced by the amount of information that is shown.